1. Field of the Invention
This invention relates to communicating with multiple data stores and more particularly relates to communicating with multiple data stores through a single connection module.
2. Description of the Related Art
Data processing systems often store and retrieve data in data stores using a coupling facility. The coupling facility is a shared data storage device and is often a shared cache. Data stores include databases, data files, and other organized data. Data processing systems typically access the data store in the coupling facility through a communication channel. Generally, the data processing system addresses each data store through a separate physical communication channel.
The coupling facility typically organizes each data store in a separate coupling facility structure. Each coupling facility structure is configured for communication through a communication channel with a data processing system. Often, each data store must be accessed through a separate communication channel between the coupling facility and one or more data processing systems. For example, accessing three data store requires three physical communication channels between the coupling facility and a data processing system as the data processing system can only address a single data store through each communication channel.
Unfortunately, the number of data stores in the coupling facility that must be accessed by the data processing system often exceeds the number of available communication channels. Consequently, one or more data processing systems are unable to access data stores. In addition, a conventional coupling facility structure just supports a single data store. This restriction is generally present simply because the data processing system is configured to address a single data store over a single dedicated physical communication channel.
FIG. 1 is a schematic block diagram illustrating one embodiment of a conventional data store management system 100. One or more data processing systems 120 may communicate through an interconnection facility 140 to one or more single management structures 160 of a coupling facility 150. The interconnection facility 140 provides communication channels. The coupling facility 150 is a shared data storage device 150. Each single management structure 160 contains one data store 180.
A first data processing system 120a may access a first data store 180a through the interconnection facility 140 to the first data store 180a of a single management structure 160. The first data processing system 120a may also access a second data store 180b through the interconnection facility 140. Unfortunately, a separate physical communication channel of the interconnection facility 140 (represented by solid arrows) is required for accessing each data store 180. If the number of data stores 180 that must be accessed by data processing systems 120 exceeds the number of physical communication channels supported by the interconnection facility 140, some of the data stores 180 will be inaccessible until a physical communication channel becomes available.
For example, if the interconnection facility 140 included sixty-four (64) physical communications channels, the data processing systems 120 will only be able to access sixty-four (64) data stores 180 in the coupling facility 150. A data processing system 120 that needed to access a sixty-fifth data store 180 in the coupling facility 150 would be forced to wait until another physical communication channel in the interconnection facility 140 becomes free, and then access the sixty-fifth data store 180 through the freed communication channel. Additional data processing systems 120b must also wait.
From the foregoing discussion, it should be apparent that a need exists for an apparatus and system that enable communication with a plurality of data stores 180 through a single communication channel. Beneficially, such an apparatus and system would reduce the number of physical communication channels required to access the plurality of data stores 180 and allow the single management structure 160 to include one or more one data stores 180.